com.facebook.buck.util.MorePosixFilePermissions.java Source code

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Here is the source code for com.facebook.buck.util.MorePosixFilePermissions.java

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/*
 * Copyright 2014-present Facebook, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may
 * not use this file except in compliance with the License. You may obtain
 * a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */

package com.facebook.buck.util;

import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableSet;

import java.nio.file.attribute.PosixFilePermission;
import java.util.Set;

public class MorePosixFilePermissions {

    private MorePosixFilePermissions() {
    }

    private static final ImmutableList<PosixFilePermission> ORDERED_PERMISSIONS = ImmutableList.of(
            PosixFilePermission.OTHERS_EXECUTE, PosixFilePermission.OTHERS_WRITE, PosixFilePermission.OTHERS_READ,
            PosixFilePermission.GROUP_EXECUTE, PosixFilePermission.GROUP_WRITE, PosixFilePermission.GROUP_READ,
            PosixFilePermission.OWNER_EXECUTE, PosixFilePermission.OWNER_WRITE, PosixFilePermission.OWNER_READ);

    private static final ImmutableMap<PosixFilePermission, PosixFilePermission> READ_TO_EXECUTE_MAP = ImmutableMap
            .of(PosixFilePermission.OTHERS_READ, PosixFilePermission.OTHERS_EXECUTE, PosixFilePermission.GROUP_READ,
                    PosixFilePermission.GROUP_EXECUTE, PosixFilePermission.OWNER_READ,
                    PosixFilePermission.OWNER_EXECUTE);

    /**
     * Convert a set of posix file permissions the unix bit representation (e.g. 0644).
     */
    public static long toMode(Set<PosixFilePermission> permissions) {
        long mode = 0;

        for (int index = 0; index < ORDERED_PERMISSIONS.size(); index++) {
            PosixFilePermission permission = ORDERED_PERMISSIONS.get(index);
            if (permissions.contains(permission)) {
                mode |= (1 << index);
            }
        }

        return mode;
    }

    /**
     * Convert a unix bit representation (e.g. 0644) into a set of posix file permissions.
     */
    public static ImmutableSet<PosixFilePermission> fromMode(long mode) {
        ImmutableSet.Builder<PosixFilePermission> permissions = ImmutableSet.builder();

        for (int index = 0; index < ORDERED_PERMISSIONS.size(); index++) {
            if ((mode & (1 << index)) != 0) {
                permissions.add(ORDERED_PERMISSIONS.get(index));
            }
        }

        return permissions.build();
    }

    /**
     * Return a new set of permissions which include execute permission for each of the
     * roles that already have read permissions (e.g. 0606 => 0707).
     */
    public static ImmutableSet<PosixFilePermission> addExecutePermissionsIfReadable(
            Set<PosixFilePermission> permissions) {

        ImmutableSet.Builder<PosixFilePermission> newPermissions = ImmutableSet.builder();

        // The new permissions are a superset of the current ones.
        newPermissions.addAll(permissions);

        // If we see a read permission for the given role, add in the corresponding
        // execute permission.
        for (ImmutableMap.Entry<PosixFilePermission, PosixFilePermission> ent : READ_TO_EXECUTE_MAP.entrySet()) {
            if (permissions.contains(ent.getKey())) {
                newPermissions.add(ent.getValue());
            }
        }

        return newPermissions.build();
    }

}